Enhanced production of heteropolysaccharide-7 by Beijerinckia indica HS-2001 in pilot-scaled bioreactor under optimized conditions involved in dissolved oxygen using sucrose-based medium

Heteropolysaccharide-7 (PS-7) is a possible alternative to xanthan or gellan used as food additives due to its properties and potential applications. Sucrose was developed as a carbon source for production of PS-7 by Beijerinckia indica HS-2001 to overcome catabolite repression against glucose. The inoculum size was established to be 5.0% (v/v) for the pilot-scaled production of PS-7 by B. indica HS-2001 based on productivity and economic aspect. The optimal agitation speed and aeration rate for cell growth of B. indica HS-2001 were found to be 495 rpm and 1.8 vvm using response surface methodology (RSM), whereas those for production of PS-7 were 440 rpm and 1.2 vvm. The optimal inner pressure for cell growth of B. indica HS-2001 in a 100 L bioreactor was 0.02 MPa, whereas that for production of PS-7 was 0.04 MPa. The production of PS-7 by B. indica HS-2001 from 30.0 g/L sucrose under an optimized inner pressure in a 100 L bioreactor was 10.20 g/L, which was 1.32 times higher than that without inner pressure. The maximal production of PS-7 under optimal conditions involved in the dissolved oxygen using the sucrose-based medium developed in this study was 1.55 times higher than that before optimization.